I believe I have the Nature 2 filter because I remember paying $90 for a replacement filter last year. I bought my 24 feet above-ground pool in 2004 and replaced the filter in 2005. I am getting ready to open my pool, just bought Ben's kit and want to know if I don't use the Nature 2 filter, what do I replace it with? Do I even use a filter? Sorry, but I'm a newbie at this. Last year, I just replaced what they gave me from the pool store and bought the opening pool kit. What a waste! I still have all the chemicals. Any help you can give me would be greatly appreciated. Thanks.